Originally published at: https://boingboing.net/2020/04/28/big-clive-examines-a-fake-uv-d.html
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I have very similar UV lamp and it’s definitely a cheap disco lamp (mine even has DMX ports). I use it for illuminating photoluminescent pigments when I’m making epoxy resin coffee tables.
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Wait - you can smell skin damage?
And, uh, do you really want to subject yourself to that?
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I never heard about this too. When I worked at university I used mercury arc lamps, but never tried to expose my skin to it. The only smell was that of ozone generated by UV-C.
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No cost is too great in the pursuit of scientific knowledge; just ask Marie Curie.
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Approved under the Trump Administration Healthcare Plan!
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Umm… how does it go inside the body?
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If you have to ask, you are a Democrat. 
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And that’s hardly the only scam about UVC he’s found.
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Yes, as well as being able to smell ozone being produced by the lamp. The thing is, really low wavelength UV light can generate ozone by itself (as he mentioned when talking about the 186 nm part of the Hg lamp spectrum) up to about 220 nm. The full UV-C spectrum can generate free radicals in organic material (like skin) which also puts off very small amounts of ozone. However, his test was not great. The amount of skin damage to reach the point where you can smell the ozone would be extreme. Think “fell asleep for hours while sunbathing in Arizona” -type sunburn. It’s also not specific, as high intensities of UV-A light also produce ROS - reactive oxidative species - that also cause that ozone smell. So if that lamp had been a high-power lamp for something like high-speed UV printing, it could have generated the ozone smell while not being anywhere close to a germicidal wavelength. Of course, if it had been a UV printing lamp, it wouldn’t have been 16 pounds - proper UV printing lamps cost thousands.
(Minor edit for clarity)
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Oh - OZONE - I knew the smell my UV lamp put out was familiar.
For those who haven’t seen my glowy things, Gonna keep spamming my link when we talk about UV stuff and rocks, until I feel loved.
So to be clear, the smell of skin damage is ozone?
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Sort of. You don’t smell ozone directly. You smell the small, volatile organics generated when ozone interacts with the tissue inside your nose. The smell from the skin damage is those same volatile organic small molecules.
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I used to dabble with home-made transmitters and a high-power radio-frequency skin burn has a very distinctive smell!
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For a proper test, one would need a photometer capable of UV-C detection. That said, I trust Big Clive’s assessment of this lamp.
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If the purpose is just to test for the presence of UV-C light, there are some chemical actinography methods that are UV-C specific. I don’t have the recipe in front of me, but I think it involves methylene blue changing color? Still not something one would have around the house, but cheaper than a UV-C radiometer.
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I have a UV water steriliser. Seeing as it’s dangerous to look at, how can I tell if the lamp is working?
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It’s easy if you are astonishingly thin-skinned.
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Cool test equipment would obviously be better; but when it’s £16 on ebay with no functional guarantees regarding accuracy, quality, fitness for purpose, UL and CE markings not being total lies, etc. I’d start with a basic economic analysis.
I have no doubt that Pacific rim factories pay substantially less per unit, but probably face broadly proportional prices(in the sense that their unit costs are lower; but 50,000 of the bit that’s expensive in unit 1 is more expensive than 50,000 of the bit that’s cheap in unit 1); and proper hard UV LEDs are expensive. Once you get to the 375-390nm mark they aren’t much more expensive than decent blues; but down at 275nm you can pay $35 for a 40mw unit.
For 12 moderately high power looking LEDs, plus housing and power supply and such, providing proper toothy UV would get pretty expensive pretty quickly.
What’s a trifle surprising here is that, while LEDs are cool and solid state and all, this is a situation where an old-school fluorescent lamp(the type without the phosphor that converts UV to visible in the ones made for normal illumination) plus little driver circuit is really cheap and really mature; and probably could deliver the promised cancer beams at roughly that price, with only a few…modest…compromises on electrical safety and build quality.
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It depends on what kind of UV water sterilizer you have, but typically, the portable ones have a water container that has a UV filter film on the plastic or glass to block the UV portion of the light. Whether it’s a mercury bulb light source or an LED, there is some visible light that the source generates that you can see through the filter.
If somehow the light source is exposed and you’re looking at it - don’t!
The thing with the really high power UV-C LEDs is, there is just a tiny bit of fluorescence that is generated in the visible range that lets you know that they are on. But it’s so dim that it just begs people to look nice and close at it - which is a bad idea because 99.999% of the light being generated is deep UV.
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